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std::shared_future::wait

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< cpp‎ | thread‎ | shared future
Revision as of 21:02, 31 May 2013 by P12bot (Talk | contribs)

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void wait() const;
(since C++11)

Blocks until the result becomes available. valid() == true after the call.

The behavior is undefined if valid()== false before the call to this function.

Contents

[edit] Parameters

(none)

[edit] Return value

(none)

[edit] Exceptions

(none)

[edit] Notes

The implementations are encouraged to detect the case when valid == false before the call and throw a std::future_error with an error condition of std::future_errc::no_state.

[edit] Example

#include <iostream>
#include <future>
#include <thread>
 
int fib(int n)
{
  if (n < 3) return 1;
  else return fib(n-1) + fib(n-2);
}
 
int main()
{
    std::shared_future<int> f1 = std::async(std::launch::async, [](){
        return fib(20);
    });
    std::shared_future<int> f2 = std::async(std::launch::async, [](){
        return fib(25);
    });
 
    std::cout << "waiting...\n";
    f1.wait();
    f2.wait();
 
    std::cout << "f1: " << f1.get() << '\n';
    std::cout << "f2: " << f2.get() << '\n';
}

Output:

waiting...
f1: 6765
f2: 75025

[edit] See also

waits for the result, returns if it is not available for the specified timeout duration
(public member function) [edit]
waits for the result, returns if it is not available until specified time point has been reached
(public member function) [edit]